• Journal of the Korea Organic Resources Recycling Association
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• v.27 no.3
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• pp.49-61
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• 2019

Swine manure has been recognized as a organic sources for composting and many research was conducted to efficiently utilize and treat. This study was to evaluate a feasibility for producing swine manure compost under various treatment with mixture of swine manure and saw dust. Treatments were designed as follows; non aerated composting pile(REF), aerated composting pile of $100L/m^3$(EXP1), and aerated composting pile of $150L/m^3$(EXP2). The total days of fermentation were 28 days and each samples were collected at every 7 days from starting of composting. Temperature sensors were installed under 30~40cm from the surface of composting pile. Inner temperature in composting piles of EXP1 and EXP2 was rapidly increased to $67{\sim}75^{\circ}C$ within 1~2 days. The elevated temperatures found during the thermophilic phase are essential for rapid degradation of organic materials. While swine manure composted, moisture content, total nitrogen, EC of EXP1, EXP2 in sample at 28 days were lower than those of REF. But, pH and organic matter of EXP1, EXP2 in sample at 28 days were higher than those of REF. After finishing fermentation experiment, maturity was evaluated with germination test. Calculated germination index(GI) at REF, EXP1 and EXP2 were 23.49, 68.50 and 51.81, respectively. The values of germination index were higher at EXP1 and EXP2 which is aerated composting piles than REF which is non aerated composting pile. According to the results, composting process by aerated static pile compost had significant effect on the reduction of required period for composting. Supplying adequate amount of air to compost swine manure will greatly reduce composting period.

• Korea Science and Art Forum
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• v.37 no.1
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• pp.249-260
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• 2019

Recently, the proportion of single-person households is on the increase in Korea, expected to reach 34.6% in 2035. Among the single-person households, Young single family households are facing greater difficulties due to high house prices in Korea. The government is expanding its support to Young single family, executing various policies such as public lease housings, private lease housings for youth, youth dormitory, etc. The purpose of this study is to understand the exact housing requirement of Young single family households who have different lifestyles with other age groups and provide base line data for youth house planning which will be in use later on. Study methods are shown below. First, this research studied the status and characteristics of Young single family households by looking into literature. Second, by studying previous studies concerned with life style and housing preferences of youth, the tool for investigating preferences and needs of housing environment by Young single family households was composed. Third, survey on characterstics of space usage, preferences and needs on flat composition, and preferences of interior design were conducted based on lifestyle of Young single family-households. The survey was conducted as an online survey using SNS for 150 Young single family holds from the age of 20 and 39, including students and office workers from December 2018 to January 2019. The results are as following. (1) Looking into the space usage characteristics, considering that various activities other than basic functions take place in bedroom and living room of small-sized Young single family households, we need to consider this additionally when planning the housing. (2) Looking into the preferences and composite needs of flat composition, the subjects demand separate bed room and more living room space, and also demand expansion of living room space where various activities take place and additional storage such as dress room in bed room (3) The preferences toward interior design show preferences toward modern style and achromatic color, a representative color. The subjects also prefer floor finishing materials normally used for living spaces, and indirect, soft lighting that uses wall. Also, there are differences between interior design preferences between students (20's) and office workers(30's) due to their different lifestyles. Research is needed to propose practical residential environment requirements and plans through a case study of actual public rental housing and a wider range of users.

• Journal of Dental Rehabilitation and Applied Science
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• v.39 no.4
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• pp.195-203
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• 2023

Purpose: This study aimed to evaluate the influence of surface sealants on the surface roughness of composite resins. Materials and Methods: The study used microfilled composite resin (Metafil CX, Sun Medical Co.) and hybrid composite resin (Aelite^TM LS posterior, Bisco). Sixty specimens (8 mm in diameter and 4 mm in height) of each composite resin type were prepared and divided into 3 groups. Each specimen was ground with 600, 1000, and 2000-grit sandpaper. The Surface roughness (Ra) values were measured using a surface roughness tester (SJ-301, Mytutoyo) before and after surface sealant application. Surface sealants, BisCover^TM LV (Bisco), Optiguard^® (Kerr), and Seal-n-Shine^TM (Pulpdent), were applied to the specimens, as instructed and observed by scanning electron microscope (JSM-7500, JEOL) and atomic force microscope (MultiMode IV, Veeco Instruments). Results: Specimens ground with 600-grit sandpaper coated with surface sealants exhibited significantly lower Ra values than the untreated group (P < 0.05). Specimens ground with 1000 and 2000-grit sandpaper showed statistically no difference. There was no significant difference in surface roughness among BisCover^TM LV, Optiguard^®, and Seal-n-Shine^TM. SEM and AFM revealed remarkably decreased microdefects on the surfaces of composite resins after surface sealant application. Conclusion: Surface sealants can influence surface roughness when applied on the rough surface of composite resins but not on highly polished composite resins.